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Color changes: Great for leaf peeping, not always for election maps

One benefit that Al Gore bestowed on all of us when he invented the internet is the ease with which we can access a plethora of election-related information at the click of a mouse. This includes color-coded maps of the United States that try to estimate the Electoral College results based on current polling data. There are several of these maps floating around the internet (I’ve referenced one on my blog sidebar.) Although each of them employs a slightly different formula for averaging polling data, the underlying premise is the same: some states are colored as solidly in either McCain’s or Obama’s column, some are shaded to indicate they are leaning to one candidate or the other, and some are colored as “toss up” states where it is too close to call. Avid consumers of election news now eagerly await the “flipping” of a state from one color to the next, and when their candidate gains a state, the blogosphere is filled with tidings of great joy.

Not surprisingly, I want to add a word of caution about overreacting to changes in the color of particular states. The colors are based on polling averages, and as you know by now, each poll has a margin of error which simply indicates how precise the poll is. Most reputable polls have a margin of error of 2-3% at the 95% confidence level. All that means is that the pollster is telling you that she estimates that the real population figure (say, the percent of all voters supporting Obama) is likely to be within 2-3% of the reported figure in the poll 95 out of 100 times.

Now suppose you see a state on a map “flip” colors from being solidly McCain to leaning McCain. Has something substantial happened? Not necessarily. If the state was “solid” McCain by the barest of margins (most of these maps require you to be ahead in the polls by more than the margin of error to be solidly in one camp or the other), and one poll comes in that has the race tied, that might be enough – depending on how the color coding is calculated – to move the state into the leaning category. But because that poll has a margin of error of 3%, or even more, we can’t actually be sure anything fundamental has changed even thought the color has changed.

Bottom Line: Changes in color are wonderful for leaf peeping, but beware of reading too much into changes on an electoral map. Read the fine print underlying the change before concluding that something fundamental is happening. In fact, as I’ll discuss in a later post, what is remarkable about this race so far is just how little change there has been in the support for the two candidates since July.